Vapor cycle refrigeration system



April 1969 J. FERNANDES 3,440,833

VAPOR CYCLE REFRIGERATION SYSTEM Filed NOV. 9, 1967 EVAPORATO INVENTOR JOSEPH FERNANDES H2 1 ATTORNEY United States Patent 3,440,833 VAPOR CYCLE REFRIGERATION SYSTEM Joseph Fernandes, Dayton, Ohio, assignor to United Airglrift Products, Inc., Dayton, Ohio, a corporation of Filed Nov. 9, 1967, Ser. No. 681,864 Int. Cl. F25b 41/00, 39/04; G05d 23/28 US. Cl. 62-196 9 Claims ABSTRACT OF THE DISCLOSURE A vapor cycle refrigeration system wherein the condenser has the form of a heat exchanger with multiple stacked passes, control means responsive to a changing condition of the flowing refrigerant being provided in the outlet manifold of the condenser to shut off flow through one set of such flow passes while flow continues through another set, the condenser automatically modulating the cooling capacity of the condenser under conditions wherein the heat rejection capacity of the condenser is far in excess of that required.

This invention relates to vapor cycle refrigeration systems, and particularly to an improved condenser therein the cooling capacity of which is automatically modulated.

Refrigeration systems of the kind to which this invention relates comprise interconnected compressor, condenser, expansion valve, evaporator and auxiliary elements. Performance in a system of the class described is vitally affected if the temperature of the fluid used to cool the condenser drops below design values or if the rate of flow of the cooling fluild is increased above design values. In either case overcooling results. The pressure and temperature of the refrigerant fluid falls to a low level. The compressor attempts a constant displacement operation so that low system pressures beyond the condenser affects the compressor suction pressure and critically reduces the evaporator boiling pressure.

In the past it has been known to compensate for this problem by controlling the compressor speed of operation, or its frequency of operation. Also, it has been known to regulate flow of the condenser cooling fluid through the use of power actuated flaps, louvers or the like. Also it has been known to remove the condenser from the refrigerant flowing system. All such modified systems are objectionable as adding to the cost, weight or complication of a refrigerating system and moreover tend to reduce system reliability.

The instant invention has in view a modification in the refrigerant vapor cycle system obviating problems of the prior art in the respects above discussed. To provide a system so characterized is an object of the invention.

According to a feature of the invention, control means is built into the condenser exit manifold, which manifold acts as a partial receiver. When the liquid temperature or pressure falls too low, a valve comprised in such control means closes off a selected portion of the condenser whereby cooling capacity is reduced. The device may be designed to adapt to the condenser to allow any number of the refrigerant circuits to be blocked off and contribute a minimal amount of heat rejection.

Other objects and structural details of the invention will appear from the following description when read in connection with hte accompanying drawing, which is a view in the main diagrammatic, or a refrigerant circulating system.

Referring to the drawing, a refrigerant flowing and control system in accordance with the illustrated embodiment of the invention includes a compressor 10 driven by a motor 11. Heated refrigerant vapor fluids are drawn from an evaporator 12 to the compressor by way of a suction 3,440,833 Patented Apr. 29, 1969 line 13. Beyond the compressor 10 the heated vapors are delivered under pressure through a line 14 to a condenser 15. There, in a manner to be discussed in greater particularity, the refrigerant is placed in heat transfer relation to a flowing cooling fluid which may be water, fuel or the like but which is in the present instance air drawn from ambient or external surroundings. Beyond the condenser the cooled refrigerant is directed by a pressure supply line 18 to the evaporator 12, being admitted to the evaporator under control of an expansion valve 19. In the evaporator the cooled refrigerant achieves a heat transfer relation to fluid to be cooled. The now heated and vaporized refrigerant is drawn from the evaporator through line 13 to compressor 10 and begins a new cycle through the systern, circulation of the refrigerant as described being continuous while the system is operating.

The condenser is comprised in the main of a heat exchange unit and while it may assume various forms it is in the present instance a device of the plate and fin type. Thus it includes upper and lower end closing plates 23 and 24 and a plurality of intermediately disposed, stacked heat conducting plates 25. Spaced apart pairs of plates 25 are held separated by spacer bars 26 at the front and back of the unit (front only shown) and by crimped fin material 27 disposed between the plates. Each pair of plates 25 and respective front and back spacers 26 define flow passes through the heat exchange unit from side to side thereof.

Adjacent pairs of plates 25 are spaced apart by bars 28 which extend from front to back of the unit along the sides thereof. This provides passageways from front to back of the heat exchange unit between the adjacent pairs of plates 25. In these passageways is other fin material 29.

A fan induced of cooling fluid, for example ambient air, is drawn through the passageways occupied by fin material 29 whereby to cool the plates 25, the passageways defined by plates 25 and occupied by fin material 27 being on one side or end of the heat exchange unit and end on the other side or end thereof. Refrigerant is communicated with such passages, the heatexchange unit having an inlet and an outlet end with respect to refrigerant flow. The inlet end is defined by a manifold 31 mounted to one side of the heat exchange unit and with respect to which heated vapor delivery line 14 is in closed communication. Heated vapor supplied through line 14 accordingly fills manifold 31 and tends to flow substantially uniformly across the heat exhanger through the several superposed flow passes defined by the stacked pairs of plates 25. Leaving the heat exchange unit proper, or core of the heat exhanger, the refrigerant enters a manifold 32 mounted to the other side of the heat exchanger in opposing relation to manifold 31, the two manifolds being welded or otherwise secured to opposing side faces of the heat exchanger core. Toward its lower end manifold 32 is relatively expanded. A cap closes an opening in its bottom and has a through central bore 33 defining the outlet and to which line 18 attaches.

Divider means in the form of a transversely disposed partition 34 is installed in manifold 32 in a manner to engage side walls thereof and the adjoining face of the heat exchanger core. The arrangement is one to define lower and upper chambers 35 and 36 in superposed relation below and above partition 34. An opening 37 in partition 34 is substantially aligned with outlet 33 and offers a major path of communication between chambers 35 and 36. Bolted to the underside of partition 34 is a housing 38 having side openings and an inturned flange 39. A through opening 41 therein aligns with opening 37. A valve cage 42 has a flanged lower end clamped between flange 39 and partition 34 and rises through opening 37 to terminate above the partition. A bearing sleeve 43 in cage 42 provides a sliding mount for the stem 44 of a conical valve 45 adapted to seat in and close opening 41. A spring 46 confined in cage 42 urges valve 45 closed.

Bolted to the underside of housing 38 is a plate 47 providing reactance to a thermal power element 48. A spring assembly 49 holds element 48 seated on plate 47. However, in accordance with the known characteristics of devices of this kind heat sensitive material within the element expands when heated and relatively projects a plunger 51, which plunger engages the underside of valve 45. Lifting or opening of valve 45 is accomplished in this manner, with closing of the valve and recompression of the thermal material in element 48 occurring under influence of spring 46 as permitted by lowering temperatures.

The partition 34 is located to divide the refrigerant flow passes into a lower set or group emptying exclusively into chamber 35 of manifold 32 and an upper set or group emptying exclusively into chamber 36 of manifold 32. In the illustrated instance only a single refrigerant flow pass opens into chamber 35, with the balance opening into chamber 36. Fluid entering chamber 35 has direct access to outlet 33. Fluid entering chamber 36 has access to outlet 33 only through controlled opening 41 in flange 39 and thence through chamber 35, the cage 42 having radial ports 52 permitting flow to opening 41. In both instances the temperature of the flowing fluid is sensed by the material in element 48 with corresponding adjustments in the position of valve 45 taking place as may result from the selection, setting and arrangement of parts. In what may be considered a normal mode of operation the thermally powered element 48 relatively projects valve 45 to a fully open position.

With valve 45 fully open the system operates as it would with no valve control. The heated vapor directed by compressor to the condenser has equal access to the refrigerant flow passes through the heat exchanger core and flows substantially equally through such passes. In manifold 32 the condensed refrigerant in chamber 36 flows readily through opening 41 and joins the refrigerant in chamber 35 in exiting from the condenser by way of outlet opening 33. From flow line 18 the condensed refrigerant is admitted by expansion valve 19 to evaporator 12 where it performs its cooling function and in a revaporized form is returned by way of line 13 to compressor 10.

While the condenser 15 has a cooling, condensing effect upon the refrigerant vapors, operation of the system under what may be considered design conditions finds the condensed refrigerant at a sufficiently high temperature, and therefore at a sufliciently high pressure, to insure a proper operation of expansion valve 19 and to avoid creation of excessively low suction pressures in line 13 and on the refrigerant side of evaporator 12. This temperature, as sensed by thermostatic power element 48, results in valve 45 maintaining a projected open position. Over-cooling of the refrigerant vapor may result, as heretofore seen, in a malfunctioning system due to decreased pressures in line 18 inhibiting proper operation of expansion valve 19. In the present instance a lowering refrigerant temperature is sensed by the material in element 48, this material allowing itself to be recompressed by spring 46. In the process, valve 45 is moved toward a seat in opening 41. Flow out of manifold chamber 36 is reduced. In a fully closed position of the valve principal flow through the condenser is only that taking place through the lower most refrigerant flow passage, or the one emptying directly into chamber 35. Whether fully closed or adjusted to a partly closed, modulating position, the valve 45 effectively reduces the capacity of condenser 15 for cooling. The temperature and pressure of the fluid reaching line 18 accordingly more nearly approaches normal values and a proper operation of valves downstream of the compressor is insured. A rise in temperature of the condensed liquid to a valve indicating overcooling conditions have been removed results in opening of valve 45 and a re- 4 turn to the normal operation above described. Valve 45 will tend, under the control of opposing forces represented by spring 46 and element 48, to assume a stabilized position, effecting such restriction upon flow of fluid from chamber 36 to chamber 35 as is indicated by the severity of conditions causing overcooling.

The partition 34 may have a small diameter opening providing for restricted by-passing flow of the liquid from chamber 36 in a closed position of valve 45, and for drainage of such chamber.

The partition 34 may be located, as indicated, anywhere along the face of the heat exchanger core to include or to exclude any selected number in the set or group emptying directly into chamber 35. As shown, it may be welded on one side to a spacer bar 28 of the heat exchanger core and on the other side held between sections of manifold 32. In closing, valve 45 effectively reduces cooling capacity of the condenser by reducing the number of refrigerant flowing passages in the condenser available for flow of the refrigerant therethrough. Manifold 32 acts as a receiver, collecting the condensed refrigerant for controlled expansion through valve '19.

In maintaining the power element 48 seated on plate 47, the spring assembly 49 provides a force for longitudinal bodily adjustment of element 48 through rotation of bolts 53 by which plate 47 is fastened to housing 38. By this means engagement and lifting of valve 45 may be made to occur at earlier and later points in the projected travel of plunger 51.

The element 48 operates in response to a changing condition of the refrigerant, in the present instance the temperature of the refrigerant. It will be understood, however, that a valve 45 or the like could be made responsive to other conditions changing in response to overcooling of the refrigerant, for example pressure. Thus, pressure responsive means located substantially in the position of the present thermostatic element 48 and associated parts could be made to sense a falling pressure brought about by lowering temperature and to respond thereto by closing valve 45 or its equivalent. Other modifications in structural details of the system, and in particular of the condensing unit 15, are possible within the scope of the invention. Some of the following claims refer to a partition and to an opening therein seating a valve. It will be understood that reference is to partition 34 and to opening 41. Housing 38 clearly could be made integral with with partition 34.

Also, the references to the refrigerant flow passage emptying directly into chamber 35 as being a lowermost passage is merely in accord with the illustrated form of the invention. The condenser and attached parts may in use assume other attitudes, as for example one substantially at right angles to that illustrated in which the refrigerant flow passages are vertically disposed. The passage or passages opening directly into chamber 35 would then be positioned endwise of the condenser.

What is claimed is:

1. In a vapor cycle refrigeration system including interconnected compressor, condenser, expansion valve and evaporator elements, an improved form of condenser including a heat exchanger having inlet and outlet ends with respect to flow of the refrigerant vapor and multiple stacked passes between said ends through which said vapor flows, said passes being continuously cooled in the operation of the system, a manifold mounted to the outlet end of said condenser in common communication with said passes and receiving cooled refrigerant, said manifold having an outlet therefrom leading to the expansion valve, divider means installed in said manifold in an intermediate position and forming with side walls of said manifold first and second chambers therein, said first chamber having at least one of said vapor flow passes emptying thereinto and communicating directly with said outlet, said second chamber having the balance of said flow passes continuously emptying thereinto and communicating with said outlet by way of said first chamber,

said divider means having an opening therein for flow from said second chamber to said first chamber, a valve adjustable to control flow through said opening, and means positioned to sense a changing condition of fluid flowing through said first chamber for adjusting said valve in accordance with such changing condition.

2. An improved condenser according to claim 1, characterized by a manifold at the inlet end of said condenser to which hot vapor is delivered by the compressor, the inlet end manifold being in common communication with said flow passes in said condenser.

3. An improved condenser according to claim 1, characterized by a further by-pass opening in said divider means constantly open for continuous communication therethrough between said chambers, said bypass opening being small in area compared to the valve controlled opening in said divider means for relatively restricted flow therethrough.

4. An improved condenser according to claim 1, characterized in that said divider means is positioned in said manifold to separate said flow passes into sets of unequal number, one of which empyties into said first chamber.

5. An improved condenser according to claim 1, characterized in that said outlet from said manifold is in the lower part of the manifold, said divider means extending transversely across the manifold to place said first and second chambers into respectively underlying and overlying relation thereto, and means suspended from said divider means in overlying relation to said outlet mounting said condition responsive means.

6. An improved condenser according to claim 1, characterized in that said condition responsive means is thermally powered and connected to said valve for direct actuation thereof, the thermally power means including a thermostat extending substantially into said outlet.

7. An improved condenser according to claim 1, wherein said flow passes are in a superposed relation to one another with said outlet being in the bottom of said manifold and said first and second chambers being in a respectively underlying and overlying relation to one another to define respectively underlying and overlying sets of flow passes in said condenser, the closing of said valve effectively shutting off flow through the upper set of passes while allowing continued flow through the lower set.

8. An improved condenser according to claim \1, characterized in that said last named means and said valve are a part of an assembly in the lower part of said manifold further comprising a housing dependent from said divider means, a reactant plate at the bottom of said housing, a thermal power element seated on said plate in a longitudinally disposed relation to said outlet, said outlet being in the bottom of the manifold and substantially receiving the lower end of said power element, the upper end of said element terminating in a plunger projected relatively to the element under rising temperatures of the fluid flowing to said outlet, said plunger entering said opening in said divider means to engage and lift said valve, said valve being arranged in an overlying relation to said divider means and being spring urged downward to seat in said opening under control of said plunger.

9. An improved condenser according to claim 8, characterized by spring means urging said thermal power element to a seat on said plate, said plate being adjustable relatively to said housing for bodily longitudinal adjustment of said power element to require greater or lesser projection of said plunger to lift said valve.

References Cited UNITED STATES PATENTS MEYER PERLIN, Primary Examiner.

US. Cl. X.R. 62--507; -36 

